The need for laser pointing for various purposes has been encountered in many applications including e.g. the automotive industry.
Consider a production line of cars where it is desired to cut through the surface of the car at a given location within an area of interest. There is a need to aim on to the selected location cutting means such as a high power laser beam that impinges on the area of interest of the car. The use of remote laser pointing techniques for e.g. cutting, welding, scribing, photolithography, drilling or dimpling constitutes an advantage over known techniques. Obviously, remote laser pointing requires high accuracy to point to the designated area. There are known in the art techniques of remote laser cutting such as programmable focusing optics. Consider, for example, a car production line in which cars move from one station to the other until the manufacturing process is completed. Assume that during manufacture, there is a station where certain actions are applied to the car including remote drilling through a certain car part, say the roof, using a laser beam. A laser device that generates the laser beam should be a priori located at a given location and the laser beam should be pointed in a precise direction towards a point of interest on the car surface for drilling therethrough. The car, in turn, should be conveyed and precisely located at the specified station in a stationary state, such that the laser beam will achieve remote drilling through the car surface at exactly the desired location and only upon finalization of the drilling action may it move to the next station. Naturally, before moving to the next station, when the car is still in a stationary state, additional remote actions (such as drilling) are applied by directing the laser beam to the desired location. Another option is to move the laser together with the moving car, preserving their relative location.
References considered to be relevant as background to the presently disclosed subject matter are listed below. Acknowledgement of the references herein is not to be inferred as meaning that these are in any way relevant to the patentability of the presently disclosed subject matter.
The article by Schafer Christian A. et al., [Proceedings of the SPIE, Volume 6454, pp. 64540A (2007)], entitled Tracking system by phase conjugation for laser energy transmission, [Department of Computer & Systems Engineering, Kobe University, Japan] discloses a new concept for a retro-directive tracking system applicable for communication and power transmission. The power transmitter utilizes a beacon emitted from the receiver to obtain information about its direction by conjugating its phase inside a nonlinear medium. Power is therefore transmitted back to the receiver by the phase conjugated beam. The power can be amplified by an array of phase conjugators which provide a large aperture so that the intensity can be increased on the receiver's photovoltaic panels compared to a single element. A system design provides the basic understanding of this setup and basic experiments are conducted with two Co-doped SrXBa1-XNb2O6 (Co:SBN) crystals. There is occurrence of interference of two beams that are generated by four wave mixing from a divergent signal beam. In areas of constructive interference, a higher intensity than the single non-interfering beams provides, was observed.
The article by Khizhnyak, A. et al of MetroLaser, Irvine, Calif., entitled Adaptive laser tracking using phase-conjugate coupled resonators, was presented at the Conference on Lasers and Electro-Optics, 2000. (CLEO 2000). The article discloses the experimental realization of a coupled laser system that employs a phase conjugate mirror (PCM) and is capable of adaptively tracking a moving output coupler. A number of approaches have been suggested in order to develop a laser system that can lock-on and track a remote object. Active laser-based systems have an advantage over passive systems because they can establish communication channels, measure target velocity and spatial coordinates, and/or deliver high optical power levels. Active systems have been demonstrated in the laboratory using PCMs; however, they have generally been limited to locking on to static or very slow moving objects. For tracking remote, high velocity targets, several problems exist including: low returned power, high Doppler frequency shift, and large temporal delays. The article illustrates that laser resonators coupled with a PCM in a Michelson type arrangement can be used to overcome some of these limitations and track a remote moving object.
Frederic, Y. M. and Bodiansky, M. in Study of a phase conjugation device for pointing and tracking applications [La Recherche Aerospatiale (English Edition) (ISSN 0379-380X), no. 6, 1990, p. 37-48. DRET-sponsored research] discusses the complexity of conventional pointing and tracking systems, which seriously handicaps their performance when submicroradian accuracies are called for, as is typically the case in intersatellite communications. Phase conjugation, an application of nonlinear optics, could provide a solution to this problem. A simple theoretical model has been developed to predict the behavior and limitations of a phase conjugate mirror when tracking a moving target. This model has been verified by means of a self-focusing experimental arrangement using an argon laser and a photorefractive barium titanate crystal in a four-wave mixing configuration.
Kotomi Kawakami et al., in Evaluation of tracking ability of a phase conjugate mirror using a CCD array and spatial light modulator for optical energy transmission [Applied Optics, Vol. 51, Issue 10, pp. 1572-1580 (2012) http://dx.doi.org/10.1364/AO.51.001572] investigated the tracking ability of an optical phase conjugator using a commercial CCD array and a projector LCD panel. This system allows one to use two separate laser oscillators for capturing interference patterns and generating phase conjugate light. Since a long coherence length is not required for the latter part, amplification of the phase conjugate light can be easily attained by using a laser oscillator for high-power applications such as machining. The wavelengths of the two laser oscillators can be independently chosen. For experimental configuration an amplification factor of 7.8×10 4 is theoretically possible. Also, a formula for the maximum tracking range is derived. The proposed system is particularly suitable for power transmission by light.
U.S. Pat. No. 4,853,528 to Robert W. Byren, Hughes Aircraft Company, entitled A self-aligning phase conjugate laser discloses a method and apparatus for providing a laser beam that is automatically aligned with a substantially rigid, stabilized platform or frame that can be oriented over a wide angular range, such as by the gimbals of a laser pointing and tracking system. A single-transverse-mode master laser oscillator is mounted on the stabilized platform which is part of the inner gimbal, which can be rotated about an elevation axis, and a multipass laser amplifier with a phase conjugation mirror and an optional nonlinear frequency-conversion device are located off the inner gimbal. An outer gimbal or pedestal mount permits rotation about an azimuthal axis. The laser oscillator and laser amplifier are coupled by means of a beamsplitter and two reflecting elements. The laser media used for the oscillator and amplifier are either the same, or compatible media having the same wavelength. In an alternative embodiment the two reflecting elements are replaced by a flexible light waveguide such as a glass fiber. The phase conjugation mirror compensates the beam for the effects of optical aberrations caused by thermally induced changes in the amplifier medium and the nonlinear medium (if used) and also compensates the beam for angular tilt and jitter in the beam line of sight due to structural flexibility and motion of the stabilized platform. Four different embodiments are described in which the phase conjugation mirror is based on stimulated Brillouin scattering, degenerate four-wave mixing, three-wave mixing, and photon echo effects, respectively.
U.S. Pat. No. 4,231,534 to Robert J. Lintell et al [The United States of America as represented by the Secretary of the Air Force], entitled Active optical tracking system discloses an active optical tracking system for air-to-air type missiles of relatively small dimensions having a pulsed laser transmitter operating through a gimbaled mirror system and a reflection receiving system connected to the guidance and control unit of the missile to direct it to a target.
U.S. Pat. No. 5,224,109 to Krasutsky et al. entitled Laser radar transceiver, discloses a gimballed optical system within a seeker head, which includes a relatively low power laser coupled to a relatively higher power laser by way of a flexible fiber optic capable to reduce the mass that must be oscillated in a scan.
U.S. Pat. No. 4,614,913 to Honeycutt et al. entitled Inherently boresighted laser weapon alignment subsystem discloses a laser weapon which has no boresighting problems in that only one laser is said to perform all the functions of search, track, and negation. The laser weapon is made to operate in both a low power cw mode and a high energy pulsed mode about the boresight. This is accomplished by the application of a material which can be rapidly switched from a transmissive to a reflective state so as to be able to utilize the same laser for search, travel, and negation; thus eliminating the need for boresight and requiring only alignment.
U.S. Pat. No. 8,217,375 to Keegan et al. entitled Integrated pod optical bench design discloses an integrated gimbal and High-Powered Multiband Laser (HPMBL) for use in an infrared countermeasure apparatus in a pod mounted on an aircraft, the improvement comprising an optical bench that connects the optical path between side-by-side mounted gimbal and high power laser; and a kinematic mounting system that prevents optical bench bending.
U.S. Pat. No. 4,664,518 to Charles E. Pfund, entitled Secure communication system, discloses a secure communication system uses narrow beam laser transmissions between an orbiting satellite and another station which may be a submerged submarine. Position reporting by a laser transmission from the submarine to the satellite provides for tracking and data transmission between the stations. For strategic use tracking of the submarine for one way data transmission is achieved from a single laser transmission from the submarine while transporting mode operation is provided for a two-way transmission data link.
U.S. Pat. No. 5,351,250 to Andrew M. Scott entitled Optical beam steering device discloses an optical beam steering device which incorporates a laser, three Brillouin shifters, a four wave mixing cell and a low power beam steering device. The first shifter and the mixing cell contain TiCl4, and the other shifters contain 20% CCl4/80% CS2. The first and third shifters frequency downshift the laser beam by δγA and δγB respectively. Light from the first shifter is amplified and provides a first pump beam input to the mixing cell. It then passes to the second shifter for frequency downshifting by δγB and returns as a second cell pump beam. Light from the third shifter passes via the low power beam steering device to the cell as a weak input signal beam. The cell responds to the pump beams and signal beam by generating a high power beam which is a phase conjugate of the signal beam and retraces part of its steered path.
U.S. Pat. No. 6,961,171 to Robert W. Byren, entitled Phase conjugate relay mirror apparatus for high energy laser system and method discloses a system for directing electromagnetic energy. The inventive system includes a first subsystem mounted on a first platform for transmitting a beam of the electromagnetic energy through a medium and a second subsystem mounted on a second platform for redirecting the beam. The second platform is mobile relative to the first platform. The beam is a high-energy laser beam. The first subsystem includes a phase conjugate mirror in optical alignment with a laser amplifier. The first subsystem further includes a beam director in optical alignment with the amplifier and a platform track sensor coupled thereto. The second subsystem includes a co-aligned master oscillator, outcoupler, and target track sensor which are fixedly mounted to a stabilized platform, a beam director, and a platform track sensor. In the best mode, the stable platform is mounted for independent articulation relative to the beam director. A first alternative embodiment of the second subsystem includes first and second beam directors. The first beam director is adapted to receive the transmitted beam and the second beam director is adapted to redirect the received beam. In accordance with a second alternative embodiment, an optical fiber is provided for coupling the beam between the first platform and the second platform.
U.S. Pat. No. 5,285,461 to Nicholas J. Krasutsky, entitled Improved laser radar transceiver discloses a gimballed optical system within a seeker head which includes a relatively low power laser coupled to a relatively higher power laser by way of a flexible fiber optic capable to reduce the mass that must be oscillated in a scan.
U.S. Pat. No. 4,102,572 to Thomas O'Meara entitled Dual-wavelength coherent optical adaptive systems discloses a dual-wavelength coherent optical adaptive systems which comprise means for adaptively forming a first beam of a first wavelength, on a target and for deriving therefrom information defining characteristics of phase perturbations in the propagation path to the target; and means responsive to said information for compensating for propagation path distortions for a second beam of a second wavelength which is simultaneously transmitted along a substantially identical path to that of said first beam.
The presentation by David Havrilla of Trumpf, Inc., entitled “Laser-Based Manufacturing in the Automotive Industry”, University of Virginia, November 2010, should also be considered as relevant prior art.
There is thus a need in the art for a new technique for pointing of a laser beam to a selected location of a surface/area of a moving object (say an area of interest in a car) e.g. for interacting (such as cutting or drilling) with the surface/area of the moving object.